patch 9.0.2129: [security]: use-after-free in call_dfunc()
Problem: [security]: use-after-free in call_dfunc()
Solution: Refresh dfunc pointer
closes: #13571
This Commit fixes a SEGV caused by a use-after-free bug in call_dfunc().
When calling check_ufunc_arg_types() from the call_dfunc() it may cause
def functions to be re-compiled and if there are too many def functions,
the def_functions array will be re-allocated. Which means, that the
dfunc pointer in call_dfunc() now starts pointing to freed memory.
So we need to reset the dfunc pointer after calling
check_ufunc_arg_types().
Let's also add a test, to ensure we do not regress.
Signed-off-by: mityu <mityu.mail@gmail.com>
Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/vim9execute.c b/src/vim9execute.c
index 997dfa0..e329559 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -548,6 +548,12 @@
if (check_ufunc_arg_types(ufunc, argcount, vararg_count, ectx) == FAIL)
return FAIL;
+ // While check_ufunc_arg_types call, def function compilation process may
+ // run. If so many def functions are compiled, def_functions array may be
+ // reallocated and dfunc may no longer have valid pointer. Get the object
+ // pointer from def_functions again here.
+ dfunc = ((dfunc_T *)def_functions.ga_data) + cdf_idx;
+
// Reserve space for:
// - missing arguments
// - stack frame